Is it rude to ask a foreign girl if she can write English?

there's this forein girl I've been talking a lot lately and I want to text her but I don't know if she can read English or write it, would it be rude to ask? If it is should I just text her and see if she understands what I'm saying? I don't want to get a no reply back cause I thinm that might mess things up. I heard her say she can't read or write English but I don;t know if she was joking because she was laughing.